Dipyrido [4,3-b] [3,4-f] indoles and process for obtaining them

ABSTRACT

The invention relates to compounds of formula:    &lt;IMAGE&gt;   wherein R&#39;1=H, OH or an alkyl group, preferably a lower alkyl group, alkylthio or alkoxy, an halogen or an amino group, R&#39;2=H or a lower alkyl group.

The present invention, in which participated Mr. Emile BISAGNI, MissClaire DUCROCQ, Mr. Christian RIVALLE, Mr. Pierre TAMBOURIN and MissFrancoise WENDLING of the "Fondation CURIE--Institut du Radium"--as wellas MM. Jean-Claude CHERMANN and Luc MONTAGNIER of the "INSTITUTPASTEUR", relates to dipyrido [4,3-b][3,4-f] indoles and a process forobtaining thereof. The invention also relates to pharmaceuticalcompositions containing the dipyrido [4,3b][3,4-f] indoles and thetherapeutic applications thereof.

It is known that 9-methoxy-ellipticine, its O-demethylated derivativeand, especially, 2-N-methyl-9-hydroxy-ellipticinium acetate, havetherapeutic properties which are interesting in the field ofcancerology; these compounds are pyrido [4,3b] carbazoles of generalformula I_(a) and I_(b) ##STR2## in which R represents CH₃ or H.

To this end, reference may be made to the following articles:

J. B. LE PECQ, C. GOSSE, NGUYEN DAT XUONG, S. CROS andC. PAOLETTI:Cancer Research 36 p 3067-3076 (1976) and

J. B. LE PECQ, C. GOSSE, NGUYEN DAT XUONG, and C. PAOLETTI: C. R. Acad.Sci. Paris Serie D 281 p 1365 (1975).

Novel compounds, dipyrido [4,3-b][3,4-f] indoles, have now been found,which also have therapeutic properties which are interesting in thefield of cancerology.

The dipyrido [4,3-b][3,4-f] indoles according to the present inventioncorrespond to formula II: ##STR3## in which: R'₁ is hydrogen, hydroxygroup, an alkyl group, preferably a lower alkyl group, an alkylthio oralkoxy group, a halogen, such as chloro, or an amino group; R'₂ ishydrogen or a lower alkyl group, preferably a methyl group.

In the present specification, the term "lower alkyl" denotes those alkylgroups having from 1 to 3 carbon atoms, and preferably the methyl group.

By way of suitable amino groups, mention may be made of the followinggroup of formula: ##STR4## in which n is between 1 and 4, preferablybetween 1 and 3, R'₆ is hydrogen of a lower alkyl group, for example CH₃group and R'₄ and R'₅ are identical or different and each represent anatom of hydrogen or a lower alkyl group; groups R'₄ R'₅ are preferablyidentical and are hydrogen, the methyl group or the ethyl group.

The invention also relates to the pharmaceutically acceptable salts ofthe dipyrido-indoles of formula (II) as well as their isomeric andtautomeric forms when they exist.

The present invention also relates to a process for obtaining saiddipyrido [4,3b][3,4f] indoles.

The process according to the present invention comprises the followingsteps of:

(1) reacting a 6-amino-isoquinoline with 3-nitro-4-chloro-pyridine toform the corresponding 6-[4'(3'-nitropyridyl)amino]isoquinoline;

(2) hydrogenating said isoquinoline thus obtained into the correspondingamino compound;

(3) reacting the corresponding amino compound with sodium nitrite toform the corresponding triazolopyridine;

(4) converting the triazolopyridine thus obtained into the correspondingdipyrido [4,3-b][3,4f] indole,

(5) possibly forming the pharmaceutically acceptable salt of thedipyrido-indole thus obtained.

The process of the invention may be represented by the followingreaction schema: ##STR5##

The starting materials used in the process of the invention aretherefore the 3-nitro-4-chloro-pyridine of formula (III) and the6-amino-isoquinolines of formula (IV).

Step 1: of the process of the invention consists in condensing the3-nitro-4-chloro-pyride of formula III with a 6-amino-isoquinoline offormula IV. This condensation may be effected according to differentprocesses well known to the man skilled in the art, these processesvarying according to the nature of the substituents R'₁ R'₂ of the6-amino-isoquinoline used in this step.

Thus, when the starting 6-amino-isoquinoline comprises no hydroxygroups, step 1 may be effected in the following manner:

The 6-amino-isoquinoline is dissolved in a suitable inert solvent, suchas 1,2-dimethoxy-ethane, a solution of dry acid, sucy as hydrochloricacid, in a dry solvent, is added, then the 3-nitro-4-chloro-pyridine isadded. The thus obtained reaction mixture is maintained at reflux untilone of the reagents has substantially completely disappeared, this beingdetermined by thin layer chromatography measurement; the solvent is thenevaporated.

When the starting 6-amino isoquinoline comprises a hydroxy group, it isadvantageous to operate at ambient temperature; the starting materialsmay be dissolved in an inert solvent, such as for exampledimethyflormamide. The reaction mixture obtained by mixture of thesolutions of the two starting materials are left at ambient temperatureuntil disappearance of the starting materials which are visible in thinlayer chromatography on silica gel. The precipitate formed is thenrecovered by conventional techniques.

Equimolar or substantially equimolar quantities of the two startingmaterials are advantageously used.

Step 2 of the process according to the invention consists in ahydrogenation of the 6-[4'-(3'-nitropyridyl)amino]isoquinoline obtainedaccording to step 1 described hereinabove. This hydrogenation iseffected in the presence of a hydrogenation catalyst, such as palladiumcharcoal. The 6-[4'-(3'-nitropyridyl)amino]isoquinoline is dissolved inan organic solvent, such as for example acetic acid; a suitable quantityof palladium charcoal is added to this solution and the mixture isstirred in a hydrogen atmosphere until the theoretical absorption ofhydrogen. The catalyst is then eliminated by filtration; the solvent isevaporated and the residue obtained is recrystallised from an organicsolvent, such as methanol, ethanol, acetonitrile, xylene, etc.

According to step 3) of the process of the invention, the correspondingtriazolopyridine is obtained by treating the6-[4'-(3'-amino-phridyl)amino]isoquinoline of formula VI with sodiumnitrite. It is advantageously to carry out this step as follows: the6-[4'-3'-amino-pyridyl amino]isoquinoline is dissolved in an orgaincacid, such as acetic acid, the mixture obtained is cooled to about 0° C.and an aqueous solution of sodium nitrite in the minimum of water isprogressively added. The reaction mixture is stirred until thetemperature returns to ambient; the precipitate formed is then washedand dried according to conventional methods.

According to step 4) of the process of the invention, thetriazolopyridine obtained according to step 3) is converted into thecorresponding dipyrido [4,3-b][3,4-f] indole. In the course of thisconversion, an opening of the triazolo ring and a cyclisation areproduced to form a dipyrido-indole of formula VIII. This step is carriedout in an inert agent, such as paraffin or phenanthrene, having a fairlyhigh boiling point to allow the conversion indicated which occuredthermally.

This step is usually carried out at a temperature of 320°-350° C.

Examples for carrying out this step will be given hereinafter.

The dipyrido [4,3-b][3,4-f] idole thus obtained is then possiblyconverted into a pharmaceutically acceptable salt.

To form these pharmaceutically acceptable salts. it is important to usethe suitable agents well known to the man skilled in the art, such ashydrochloric, hydrobromic, succinic, lactic, acetic, phosphoric acidsand all other acids commonly used for forming such salts.

The reaction schemas of the preferred proceedings for carrying out theprocess according to the invention will be indicated hereafter:

PROCEEDING n°1:

This proceeding relates to the obtaining of dipyrido-indoles of formulaII hereinabove in which R'₁ is hydrogen and R'₂ is an alkyl group, forexample the methyl group; this proceeding is represented by thefollowing diagram for the compound of formula II in which R'₂ is amethyl group: ##STR6##

This proceeding will be illustrated by Examples 1 to 4 hereinafter.

PROCEEDING n°2

This proceeding relates to the obtaining of dipyrido-indoles of formulaII hereinabove in which R'₁ is the hydroxy group and R'₂ is hydrogen ora lower alkyl group. ##STR7##

The compounds 19 to 26 described hereinafter in the illustrativeexamples have been synthesised according to this proceeding, incompounds 19 to 25, R'₂ =H and R is as defined hereinbelow: ##STR8##

According to this proceeding, the product of formula 15, which is astarting material according to the process of the invention and whichmay be in its tautomeric form (15a). ##STR9## may be prepared fromcinnamic acid of formula (12), by the process which comprises the stepsof forming the corresponding azide (13); of effecting a cyclisation toform the corresponding isoquinoline and finally of eliminating theprotector group of the amino group to abtain the b5-methyl-6-amino-isoquinolone of formula (15). The proceeding 2 is thencarried out according to the process defined previously to obtain thecompound according to the invention of formula XIX in which R is thehydroxy group (compound 19). The hydroxy group of this compound may thenbe substituted by an atom of chlorine, an amino group, such as forexample the following groups, to obtain compounds 19 to 26. ##STR10##

The cinnamic acid of formula (12) used as starting product in proceedingn°2 defined hereinabove may be obtained in different ways. Threeproceedings will be indicated hereinafter which are suitable forobtaining the cinnamic acid of formula (12) [proceedings (a) to (c)]##STR11## R'₂ being as defined previously.

According to this proceeding, the cinnamic acid of formula (12) isobtained from the 2-methyl-3-amino-benzonitrile of formula (10a) by theprocess which comprises the steps of converting the amino group of thiscompound into the acetylamino group to form the compound of formula(10b); of converting the cyano group of the2-methyl-3-acetylamino-benzonitrile into the aldehyde group to form thecompound of formula (11) and then of condensing the aldehyde group ofthis latter compound with malonic acid to form the cinnamic acid offormula (12). This proceeding is illustrated by example 5 hereinafter.##STR12## R'₂ being as defined previously.

This proceeding comprises the steps of converting2-methyl-3-nitroaniline of formula (30) into (2-methyl-3-nitro-phenyl)chloropropionic acid of formula (31), of converting this latter compoundinto 2-methyl-3-nitro-cinnamic acid of formula (32) by elimination ofHCl and then in converting the nitro group of this compound into theacetylamino group, passing through the stage of the amino group (formula33) to form the compound of formula (12).

This proceeding will be illustrated by example 13 hereinafter.

PROCEEDING (C)

This proceeding is suitable for obtaining the compound of formula (12)in which R'₂ is--CH₃ ##STR13##

This proceeding comprises the steps of converting the chloro-methylgroup of the compound of formula (A) into an aldehyde group [compound offormula (B)], of condensing this aldehyde group with malonic acid toform the cinnamic acid of formula (C), of reducing the nitro group ofthe compound of formula (C) into an amino group [compound of formula(D)] which is then converted into the acetylamino group to obtain thecompound of formula (12). This proceeding will be illustrated by example12 hereinafter.

The intermediate compounds obtained when carrying out proceeding n°2hereinabove and proceedings (a), (b) and (c), are within the scope ofthe invention, as well as their isomeric and tautomeric forms when theyexist.

Among the compounds of the present invention, particular mention may bemade of the following:

5,11-dimethyl-dipyrido [4,3-b][3,4-f] indole;

2,5,9,11-tetramethyl dipyrido [4,3-b][3,4-f] indolinium diacetate;

5,11-dimethyl-dipyrido [4,3-b][3,4-f] indole acetate.

5,11-dimethyl-dipyrido [4,3-b][3,4-f] indole dihydrochloride.

1,2-dihydro-1-oxo-4-methyl dipyrido [4,3-b][3,4-f] indole;

1-chloro, 5-methyl dipyrido [4,3-b][3,4-f] indole;

1-(α-diethylaminopropyl)amino-55-methyl-dipyrido [4,3-b][3,4-f] indole;

1-(α-dimethylaminopropyl)amino-5-methyl-dipyrido [4,3-b][3,4-f]indole;

1-(β-dimethylaminoethyl)amino-5-methyl-dipyrido [4,3-b][3,4-f]indole;

1-[α-methyl(δ-diethylamino butyl)amino]-5-methyl-dipyrido[4,3-b][3,4-f]indole;

1-[(Γ-amino-propyl)amino]-5-methyl-dipyrido [4,3-b][3,4-f]indole;

1,2-dihydro-1-oxo-5,11 dimethyl-dipyrido [4,3-b][3,4-f]indole.

The invention also relates to antiviral and antitumoral pharmaceuticalcompositions containing a therapeutically effective quantity of acompound according to the invention of formula II, in combination with apharmaceutically inert excipient. The pharmaceutical compositionsaccording to the invention may be particularly in the form of solutionsinjectable by the intravenous (i.v.) or intramuscular (i.m.) route.

The antitumoral properties of the compounds according to the inventionhave been determined by their curative action on inoculated test L-1210leukemia. This leukemia has in fact enabled numerous active compoundsused in human therapeutics to be selected.

[ZUBROD C. G., Proc. Nat. Acad. Sci. 1972, 69, 1042-1047 and SCHEPARTZSA. SCREENING, 1971, CANCER Chemother. Rep. Part 3 vol.2 p.3].

This leukemia is maintained in ascitic form by passage (i.p. route) onCBD1 (C57 B16 × DBA/2)Fl mice. The preparations to be tested areinjected by the intraperitoneal route at least one day after theincoculation of the cells (one injection only). The results areexpressed in increased life span percent(ILS %) according to KESSEL etal. Cancer Res. 1971, 31, 1883-1887) or in percentage of the number ofcells killed by the product (the survial of the animals is proportionalto the number of cells injected).

The protective power of the compounds according to the invention havealso been sought on the Friend viro-induced leukemia (J. Exp. Med.1957-105 -307-318) and it has been determined that the compoundsaccording to the invention are antiviral and antitumoral agents.

The study of the development of the MOLONEY viro-induced sarcoma (Nat.Cancer. Inst. Monograph 22, 139-142,1966) has also made it possible todetermine that the compounds according to the invention are antiviraland antitumoral agents.

The toxic dose and the acute toxicity in vivo, i.e. the lethal doses LD100 and LD 50, have also been determined.

Furthermore, it has been shown that the compounds according to theinvention are cytotoxic at concentrations included between 0.2 and 10μm.and that compound 21 according to the invention is just as active, ormore so, than products presently used as antitumoral agents.

The invention will now be illustrated by the following non-limitingexamples.

EXAMPLE 1 Preparation of 5,11-dimethyl dipyrido [4,3-b][3,4-f] indole(compound of formula 8) A-5,8-dimethyl6-[4'(3'-nitro-pyridyl)amino]isoquinoline of formula (5).

36g of 5,8-dimethyl-6-amino-isoquinoline of formula (4) were dissolvedin 1.5 of 1,2-dimethoxy-ethane; 33.14 g of 3-nitro-4-chloro-pyridine offormula (3) were added, then 95.85 ml of a solution of dry hydrochloricacid in ether assayed at 4.363 M [2 molar equivalents with respect tothe amino-isoquinoline of formula (3)] were added.

After 192 hours of heating with reflux, the solvent was evaporated, theresidue was taken up with 1.5 1 of water with stirring for 1 hour andthe insoluble precipitate was filtered off to give 1.7 g of3-nitro-4-hydroxy-pyridine.

With constant checking with a pH meter, potassium carbonate wasprogressively added to the aqueous phase and the precipitate whichappears from pH 4 was filtered off when pH 5.5 was reached. Afterdrying, said precipitate was recrystallised from benzene and 17.6 g or28.6%, of yellow micro-crystals were thus obtained, melting point 206°C., corresponding to the expected compound.

    ______________________________________                                        Analysis: C.sub.16 H.sub.14 N.sub.4 O.sub.3                                                   C          H      N                                           ______________________________________                                        % calculated   65.29       4.80   19.04                                       % found        65.09       4.81   18.86                                       ______________________________________                                    

By making alkaline the mother liquors up to pH 10, 13 g or 36%, of theamino-isoquinoline of formula (4), were recovered, melting point: 140°C. after crystallisation.

B/5,8-dimethyl-6-[4'-(3'-amino-pyridyl)amino]-isoquinoline of formula(6).

20g of nitrated derivative of formula (5) were dissolved in 1 liter ofabsolute ethanol, to which were added 2 g of 10% palladium charcoal andthe whole was stirred in a hydrogen atmosphere at ambient pressure andtemperature until the theoretical quantity of hydrogen has beenabsorbed. After filtration of the catalyst, the solvent was evaporatedand the residue recrystallised from ethanol to give 16.9 g (93.7%) ofbeige crystals, melting point =235°-250° C. with decomposition,corresponding to the expected compound crystallised with 1/2 mole ofethanol.

    ______________________________________                                        Analysis: C.sub.16 H.sub.16 N.sub.4, 1/2C.sub.2 H.sub.5 O.sub.H                                  C        H      N                                          ______________________________________                                               % calculated                                                                              71.05    6.66   19.50                                             % found     70.78    6.77   19.18                                      ______________________________________                                    

C/1-(5',8'-dimethyl-isoquinolyl)][4,5-c]triazolo pyridine of formula(7).

16.8 g of the amine of formula (6) were dissolved in 300 ml of aceticacid, cooled to about 0° C. and 4.83g of sodium nitrite dissolved in 150ml of water were progressively added thereto, drop by drop and inmaintaining the cold. The reaction mixture was maintained cold, understirring, for 2 hours, then 1 hour allowing it to return to ambienttemperature; the solent was evaporated, the residue was taken up with300 ml of water and the insoluble precipitate was filtered.

After recrystallisation from ethanol, 14.8 g (84.5%) of pale yellowcrystals were formed, melting point 215°-220° C., corresponding to theexpected product.

    ______________________________________                                        Analysis: C.sub.16 H.sub.13 N.sub.5                                                            C        H        N                                          ______________________________________                                               % calculated                                                                            69.80    4.76     25.44                                             % found   69.67    4.77     25.23                                      ______________________________________                                    

D/5,11-dimethyl-dipyrido [4,3-b][3,4-f]indole of formula (8)

12 g of the triazolopyridine of formula (7) were mixed with 39 g ofparaffin with a melting point of 54°-56° C. and the whole was heatedunder a nitrogen atmosphere until the gaseous emission was complete i.e.for 20 to 25 minutes.

After having left the reaction mixture to cool, 100 ml of heavypetroleum ether (boiling point under normal pressure: 100°-140° C.),were added, the mixture was heated up to boiling and the insoluble blacksolid was filtered off. This latter was taken up with ethanol in thepresence of animal charcoal, filtered, concentrated and filtered in thecold, then recrystallised from pyridine to give 5.4 g (40.6%) of yellowmicro-crystals, non-melting at 350° C.

    ______________________________________                                        Analysis: C.sub.16 H.sub.13 N.sub.3                                                            C        H        N                                          ______________________________________                                               % calculated                                                                            77.71    5.30     16.99                                             % found   77.52    5.32     16.98                                      ______________________________________                                    

EXAMPLE 2 Preparation of2,5,9,11-tetramethyl-dipyrido[4,3-b][3,4-f]indolinium of formulaIX[X=CH₃ COO].

274 g of the compound of formula (8), obtained according to example 1,were suspended in 750 ml of acetone and heated with reflux for 6 hours,in the presence of a large excess of methyl iodide (1,42 g). Afteraddition of the same quantity of methyl iodide, heating was againeffected with reflux for 14 hours; the reaction mixture was then cooledand 487 mg (92%) of the insoluble product corresponding to the diiodide[compound of formula (IX) in which X=I] were filtered off.

    ______________________________________                                        Analysis: C.sub.18 H.sub.19 I.sub.2 N.sub.3                                                    C        H        N                                          ______________________________________                                               % calculated                                                                            40.68    3.58     7.91                                              % found   40.55    3.67     7.88                                       ______________________________________                                    

450 mg of the compound obtained, previously dissolved in 100 ml ofwater, were passed over an exchange resin column ("DOWEX 1X2")containing acetate ions and the solvent was evaporated. The residue wastaken up with isobutyl alcohol to give the expected product in the formof yellow-orange microcrystals, metling point 230°-235° C. It gave onestain by chromatography on a thin alumina layer with the methanol-watermixture (4/l1 v/v) as eluent; the nuclear magnetic resonance (NMR)spctrum indicates that it is the expected compound, but its centesimalanalysis corresponds to the desired product partially hydrated.

EXAMPLE 3

Preparation of 5,11-dimethyl dipyrido-[4,3-b][3,4-f] indole.

1 g of the compound of formula (8), obtained according to example 1, and20 ml of acetic acid were heated at boiling point and the excess ofacetic acid was immediately evaporated. The residue, taken up withacetone and filtered yielded 1 g of insoluble precipitate in the form ofyellow ochre micro-crystals, non-melting at 310° C., and correspondingto the monohydrate of the expected compound.

    ______________________________________                                        Analysis: C.sub.18 H.sub.19 N.sub.3 O.sub.3                                                     C        H        N                                         ______________________________________                                               % calculated                                                                             66.44    5.89     12.92                                            % found    66.58    5.83     12.79                                     ______________________________________                                    

EXAMPLE 4 5,11-dipyrido-[4,3-b][3,4-f]-indole dihydrochloride

200 mg of the base of formula (8) obtained according to example 1 weredissolved in 20 ml of absolute ethanol, 1 ml of ethanol saturated byhydrochloric acid was added and the solvent was evaporated in a waterbath under reduced pressure. The residue was taken up with acetone andfiltered off to yield 200 mg of ochre micro-crystals, non-melting at310° C. and corresponding to the expected dihydrochloride in the form ofmonohydrate.

    ______________________________________                                        Analysis: C.sub.16 H.sub.17 Cl.sub.2 N.sub.3 O                                                 C       H       Cl    N                                      ______________________________________                                               % calculated                                                                            56.80   5.02    21.01 12.43                                         % found   56.34   4.78    21.20 12.56                                  ______________________________________                                    

EXAMPLE 5 Preparation of1,2-dihydro-1-oxo5-methyl-dipyrido-[4,3-b][3,4-f] indole (compound 19).(A) 2-methyl-3-acetylamino-benzaldehyde of formula (11)

39g (0.3 mole) of 2-methyl-3-amino-benzonitrile were dissolved in 75 mlof acetic acid, 30 ml (0.3 mole) of acetic anhydride were added, themixture was heated with reflux for 5 minutes, and cooled. The solidobtained was filtered off and the evaporation of the solent furnished anadditional quantity of solid which was added to the preceding one. Afterrecrystallisation of the whole from toluene, 44 g (95%) of colorlessflakes were obtained, with a melting point of 160° C. l

    ______________________________________                                        Analysis: C.sub.10 H.sub.10 N.sub.2 O                                                            C        H       N                                         ______________________________________                                        % calculated       68.95    5.79    16.08                                     % found            68.82    5.83    15.99                                     ______________________________________                                    

(B) 2-methyl-3-acetylamino-cinnamic acid of formula (12)

In a 61 three-necked flask were introduced 60 g (0.34 mole) of thenitrile of formula (10) and 1 liter of 50% diluted formic acid, then themixture was heated at boiling point. Maintaining the whole with reflux,120 g of Raney alloy were added at 5 times, at intervals of 30 minutes;the mixture was left 30 minutes more at reflux and the salts and theexcess of insoluble reagent were filtered.

The precipitate was washed in hot water and the whole of the filtratewas extracted with chloroform, at least ten times with 500 ml ofchloroform each time.

The evaporation of the organic phase gave a residue which distilled,giving 39 g of a product (boiling point 11=210°-225° C.) correspondingto the mixture of the starting nitrile and the aldehyde of formula (11),i.e. the 2-methyl-3-acetylamino-benzaldehyde. If crystallisation waseffected from benzene or toluene, fine, colorless needles were obtained,melting point: 124°-128° C.

    ______________________________________                                        Analysis: C.sub.10 H.sub.11 NO.sub.2                                                             C        H       N                                         ______________________________________                                        % calculated       67.78    6.26    7.91                                      % found            68.07    6.27    8.05                                      ______________________________________                                    

The preceding mixture (38 g), crude from distillation, was dissolved in50 ml of dry pyridine; it was added all at once to a solution of 300 mlof pyridine containing 22.5 g of malonic acid and 1 ml of piperidine,and the whole was heated with reflux for 11/2 hours. The pyridine wasevaporated under reduced pressure and the residue was treated by asolution of sodium hydroxide in excess in the presence of chloroform.

After decantation, the evaporation of the chloroform gave a residueconstituted by a fraction of starting nitrile of formula (10).

The acidification of the alkaline layer by hydrochloric acid gave theacrylic acid of formula (12), which was recrystallised from acetic acid,giving 25g (34% with respect to the quantity of nitrile of formula (10)used of colorless flakes, melting point=265°-267° C.

    ______________________________________                                        Analysis: C.sub.12 H.sub.13 NO.sub.2                                                             C        H       N                                         ______________________________________                                        % calculated       65.74    5.98    6.39                                      % found            65.58    6.12    6.52                                      ______________________________________                                    

(C) 2-methyl-3-acetylamino-cinnamoylazide of formula (13)

The acrylic acid of formula (12) (36 g) was added to a solution of 17 gof triethylamine in 150 ml of acetone and the whole was cooled up to 0°C. Maintaining the temperature below 0° C., a solution of 24.3 g ofethyl-chloroformate in 150 ml of acetone was added drop by drop, themixture was stirred at 0° C. for 1 hour, then the solution formed from16 g of sodium azide and 40 ml of water was progressively added. Thereaction mixture was again stirred in the cold for 1 hour after the endof the addition and 27.8 g(71%) of a colorless solid corresponding tothe desired azide which was decomposed by melting from 150° C., werefiltered off. The evaporation of the acetone of the mother liquors in awater bath under reduced pressure, and not exceeding 30° C. gave anadditional quantity of the expected compound which was then coloredyellow. This product was used in the synthesis without any otherpurification.

(D) 1-hydroxy-5-methyl-6-acetylamino-isoquinoline or5-methyl-6-acetylamino-1-isoquinolone of formula (14).

The mixture constituted by 1.51 of diphenyl ether and 33 g oftributylamine was heated to 240° C. in a 41, three-necked flask. 41g ofthe azide of formula (13) previously dried in a vacuum desiccator wereplaced in suspension in 300 ml of diphenyl ether and the mixture wasadded to the preceding solution maintained under violent stirring, insmall portions but as rapidly as possible and continuing to heat toavoid the temperature dropping to below 220° C.

After the end of the addition, heating was again effected to 240° C. andthe reaction mixture was maintained at this temperature for 10 minutes,then it was left to cool. The precipitate formed was filtered, washed inbenzene and recrystallised from ethanol, in which it was very sparinglysoluble, to give 25 g (69%) of colorless microcrystals, non-melting at320° C.

    ______________________________________                                        Analysis: C.sub.12 H.sub.12 N.sub.2 O.sub.2                                                      C        H       N                                         ______________________________________                                        % calculated       66.65    5.59    12.96                                     % found            66.98    5.64    12.87                                     ______________________________________                                    

(E) 5-methyl-6-amino-1-isoquinolone of formula (15)

The mixture formed by 500 ml of ethanol, 100 ml of hydrochloric acid and25 g of the compound of formula (14) was heated with reflux for 21/2hours. The evaporation of the solvent gave a residue which was taken upwith hot water, filtered, and the alkalinisation of the filtrate by Nsodium hydroxide gave 16.3 g (81%) of a compound which recrystallised inthe form of colorless needles, melting point=260°-285° C. withdecomposition.

    ______________________________________                                        Analysis: C.sub.10 H.sub.10 N.sub.2 O                                                            C        H       N                                         ______________________________________                                        % calculated       68.95    5.79    16.08                                     % found            68.97    5.83    15.85                                     ______________________________________                                    

(F) 5-methyl-6-[4'-(3'-nitro-pyridyl)amino]1-isoquinolone of formula(16)

b 17.4g of the compound of formula (15) were dissolved in 400 ml ofdimethyl formamide (DMF); a solution of 15.9 g of chloronitro-pyridineof formula (3) in 100 ml of DMF was added and this mixture was left atambient temperature for 12 days. The precipitate formed was filteredoff; the evaporation of the solvent under reduced pressure gave anadditional quantity of solid and the whole of said latter was taken upwith hot water then rendered alkaline by N sodium hydroxide. Theprecipitate formed was recrystallised from DMF, giving 21.3g (72%) ofyellow prisms non melting at 330° C. and corresponding to the compoundof formula 16.

    ______________________________________                                        Analysis: C.sub.15 H.sub.12 N.sub.4 O.sub.3                                                      C        H       N                                         ______________________________________                                        % calculated       60.80    4.03    18.91                                     % found            60.46    4.08    18.62                                     ______________________________________                                    

When the reaction has been effected in the presence of an excess of 1 to3% of the 3-nitro-4-chloro-pyridine of formula (3), apart from theproduct described hereinabove, from 10to 15% of a secondary product,less soluble in the DMF, was isolated, which was recrystallised fromthis solvent in the form of red prisms, non fusible at 330° C. Itcorresponds to 3-nitro-4-amino di [N-1,N-4(1'-hydroxy-5'-methyl-6'-isoquinolyl)pyridine].

    ______________________________________                                        Analysis: C.sub.26 H.sub.19 N.sub.5 O.sub.4, 1/2H.sub.2 O                                          C       H       N                                        ______________________________________                                        % calculated         64.95   4.35    14.38                                    % found              64.72   4.19    14.28                                    ______________________________________                                    

(G) 5-methyl-6-[4'-(3'-amino-pyridyl)amino]isoquinolone of formula (17)

12.6 g of the preceding nitrated derivative were dissolved in 500 ml ofacetic acid; 0.6 g of 10% palladium charcoal was added and stirring waseffected under a hydrogen atmosphere until the theoretical quantity ofhydrogen was absorbed. 500 ml of acetic acid were added, the mixture washeated to dissolve the precipitate formed, the catalyst was filtered,the solvent was evaporated and the residue was dissolved in water. Afteralkalinisation up to pH 9, the precipitate was filtered andrecrystallised in acetonitrile to give 10.2 g (84.3%) of creammicro-crystals, corresponding to the hydrate of the amine of formula(17).

    ______________________________________                                        Analysis: C.sub.15 H.sub.16 N.sub.4 O.sub.2                                                      C        H       N                                         ______________________________________                                        % calculated       63.86    5.67    19.71                                     % found            63.84    5.44    19.47                                     ______________________________________                                    

(H) 1-[6'-(1',2'-dihydro-1'-oxo-5'-methyl-isoquniolyl)]triazolo[4,5-c]-pyridine of formula (18).

In a 500 ml, three-necked flash provided with a thermometer, amechanical stirrer and a dropping funnel, 10.2 g of the amine of formula(17) and 70 ml of acetic acid were mixed; the reaction mixture wascooled up to about 0° C. and a solution of 3 g of sodium nitrate in theminimum of water was progressively added. Stirring was continued for 1hour, allowing the reaction mixture to return to ambient temperature;the precipitate was then filtered, washed in water and dried. 8.3 g(83.5%) of colourless microcrystals were thus obtained; melting point309°-310° C., corresponding to the hydrate of the triazolopyridine offormula (18).

    ______________________________________                                        Analysis: C.sub.15 H.sub.15 N.sub.5 O.sub.2                                                   C         H         N                                         ______________________________________                                        % calculated    61.01     4.44      23.72                                     % found         60.92     4.15      23.44                                     ______________________________________                                    

(I) 1,2-dihydro-1-oxo-5-methyl-dipyrido [4,3-b][3,4-f]indole of formulaXIX with R=OH: compound 19

8 of triazolopyridine of formula (18) were added to 60 g of meltedphenanthrene, then heated to 340° C., and the reaction mixture wasmaintained under stirring at this temperature for 20 minutes, then leftto cool. The phenanthrene was extracted with petroleum ether or hexaneand the insoluble residue was recrystallized from DMF to give 4.2 g(58%) of grey micro-crystals non-fusible at 310° C. and corresponding tothe hemi-hydrate of the product of formula (19).

    ______________________________________                                        Analysis: C.sub.15 H.sub.11 N.sub.3 O, 1/2 H.sub.2 O                                            C        H        N                                         ______________________________________                                        % calculated      69.75    4.68     16.27                                     % found           70.04    4.40     16.14                                     ______________________________________                                    

EXAMPLE 6 1-chloro-5-methyl-dipyrido [4,3-b][3,4-f] indole (compound offormula XIX with R=Cl: compound 20)

1.5 g of the dipyrido-indole (compound 19) was mixed with 250 ml ofphosphorus oxychloride containing 1.5 g of phosphorus pentachloride andthe mixture was heated with reflux for 20 hours. The excess ofoxychloride and pentachloride was eliminated in a water bath underreduced pressure and the residue was taken up with tepid water, onseveral times and in stirring on each time for 1 hour, until exhaustion.The aqueous filtrates combined and cooled were neutralised by a solutionof sodium or potassium carbonate and the precipitate formed, filteredoff then dried, was recristallised from DMF, giving 875 mg (54%) ofyellow micro-crystals, non-melting at 320° C. and corresponding to thehemi-hydrate of the chlorinated derivative 20.

    ______________________________________                                        Analysis: C.sub.15 H.sub.10 N.sub.3 Cl, 1/2H.sub.2 O                                              C      H      N    Cl                                     ______________________________________                                        % calculated        65.10  3.97   15.19                                                                              12.84                                  % found             64.77  3.92   14.97                                                                              13.21                                  ______________________________________                                    

EXAMPLE 7 1-Γ-diethylaminopropyl)amino-5-methyl-dipyrido-[4,3-b][3,4-f]indole (compound of formula XIX with ##STR14##

The mixture, constituted by 875 mg of the chlorinated derivativeobtained according to example 6 hereinabove and 10 g ofΓ-diethyl-aminopropylamine, was heated in an oil bath at 150° C. for 30minutes and the excess of amine was eliminated in a water bath underreduced pressure. The residue was extracted three times with 60 ml ofboiling benzene and the insoluble residue was taken up with chloroformin the presence of sodium hydroxide. After washing of the chloroformlayer in water, the chloroform was evaporated, the residue was taken upwith the benzene previously used and the whole was concentrated up toabout 50 ml and cooled. The filtration of the solid in suspension gave180 mg (15%) of yellow microcrystals, melting point=215°-218° C.,corresponding to the expected amine crystallized with a molecule ofwater.

    ______________________________________                                        Analysis: C.sub.22 H.sub.27 N.sub.5,H.sub.2 O                                                     C       H       N                                         ______________________________________                                        % calculated        69.63   7.70    18.46                                     % found             70.02   7.39    18.29                                     ______________________________________                                    

It has been ascertained that by operating with an excess ofΓ-diethylaminopropylamine, the yield may be improved. According to thisembodiment, the mixture, constituted by 4 g of the chlorinatedderivative obtained according to example 6 hereinabove and 100 ml ofΓ-diethylaminopropylamine, was heated with reflux for 4 hours and theexcess of amine was eliminated under reduced pressure. The residueobtained was taken up with a N sodium hydroxide solution and theprecipitate formed, filtered off and dried, was recrystallised fromxylene to give 4.1 g (73%) of the expected derivative which hascrystallized with a molecule of water.

    ______________________________________                                        Analysis: C.sub.22 H.sub.27 N.sub.5,H.sub.2 O                                                     C       H       N                                         ______________________________________                                        % calculated        69.63   7.70    18.45                                     % found             69.82   7.49    18.33                                     ______________________________________                                    

EXAMPLE 81-(Γ-dimethylaminopropyl)amino-5-methyl-dipyrido-[4,3-b][3,4-f] indole(compound of formula XIX) ##STR15##

The procedure according to the first proceeding described in example 7was carried out, in heating at boiling point dimethylamine-propylaminefor 7 hours. After a treatment identical to the one mentionedhereinabove, the product was recrystallized from benzene to give paleyellow micro-crystals, melting point: 240° C., corresponding to thehemi-hydrate of the expected product.

    ______________________________________                                        Analysis: C.sub.20 H.sub.23 N.sub.5, 1/2 H.sub.2 O                                                 C       H       N                                        ______________________________________                                        % calculated         70.09   7.00    20.44                                    % found              70.27   6.85    20.13                                    ______________________________________                                    

By operating according to the embodiment described in example 7hereinabove, a yield of 73% has been obtained. According to thisembodiment, the chlorinated derivative of example 6 with a large excessof Γ-dimethylaminopropylamine was heated with reflux for 4 hours. Afterelimination of the excess of amine under reduced pressure, the productwas recrystallised from benzene and 73% of micro-crystals were obtained,the melting point of which is 240° C.; this product corresponds to thehemi-hydroxide of the expected product.

1 g of the compound obtained hereinabove was dissolved in 30 ml ofethanol saturated by hydrochloric acid, the mixture was heated toboiling point and cooled immediately. The precipitate formed isrecrystallized from ethanol and 1 g of colourless needles was obtained,melting point=266°-268° C., corresponding to the hydratedtri-hydrochloride of compound 22 hereinabove.

    ______________________________________                                        Analysis: C.sub.20 H.sub.23 N.sub.5, 3HCl, H.sub.2 O                                               C      H      N    Cl                                    ______________________________________                                        % calculated         52.11  6.08   15.20                                                                              23.12                                 % found              51.72  6.21   14.83                                                                              22.88                                 ______________________________________                                    

EXAMPLE 9 1-(β-dimethylaminoethyl)amino-5-methyl-dipyrido-[4,3-b][3,4-f]indole (compound of formula XIX) ##STR16##

The procedure was the same as in examples 7 and 8 above, in heating thechlorinated compound 20, in β-dimethylaminoethylamine at boiling pointfor 15 hours. After a treatment identical to those mentioned in the twopreceding cases, the product was recrystallised, then taken up withhydrochloric ethanol to form the corresponding trihydrochloride, whichwas recrystallised from ethanol in colourless prisms, melting point262°-269° C., corresponding to the dihydroxide of the trihydrochlorideof the expected compound 23 : C₁₉ H₂₁ H₅. Yield 37%.

    ______________________________________                                        Analysis: C.sub.19 H.sub.21 N.sub.5, 3HCl 2 H.sub.2 O                                              C      H      N    Cl                                    ______________________________________                                        % calculated         49.08  6.02   15.07                                                                              22.93                                 % found              49.58  5.77   14.52                                                                              23.26                                 ______________________________________                                    

EXAMPLE 101-[(α-methyl-δ-diethylamino-butyl)-amino]-5-methyldipyrido-[4,3b][3,4-f]indole (compound of formula XIX with R=NH--CH--CH₂ --CH₂ --CH₂ --N(C₂H₅)₂ i.e. compound 24).

500 mg of the chlorinated derivative obtained according to example 6hereinabove were placed in 10 ml of 2-amino-5-diethylamino-pentane andthe mixture was heated with reflux of the amine for 13 hours, under anitrogen atmosphere and protected from the light. The excess of aminewas eliminated and the residue was taken up with a N sodium hydroxidesolution. The precipitate formed was filtered off, washed in water,dried and recrystallised from toluene to give 120 mg (17%) of yellowmicro-crystals, melting at around 160° C.

    ______________________________________                                        Analysis: C.sub.24 H.sub.31 N.sub.5 H.sub.2 O = 405.5                                                C      H      N                                        ______________________________________                                        % calculated           71.08  7.71   17.22                                    % found                70.78  7.94   17.59                                    ______________________________________                                    

EXAMPLE 11 1-[(γ-amino-propyl)amino]-5-methyl-dipyrido [4,3-b][3,4-f]indole.

(Compound of formula XIX with R=NH--CH₂ --CH₂ --CH₂ --NH₂ i.e. compound25).

The procedure is the same as in example 7 with 400 mg of the chlorinatedderivative obtained according to example 6 and 10 ml of1,3-diamino-propane, in heating with reflux for 1 hour. The excess of1,3-diamino-propane was eliminated, the residue was taken up with aN-sodium hydroxide solution and the precipitate was filtered off. Thislatter was recrystallised from dimethylformamide to give 190 mg (42%) ofpale yellow micro-crystals, melting point=268°-269° C.

    ______________________________________                                        Analysis: C.sub.18 H.sub.19 N.sub.5,0.33 H.sub.2 O = 311                                          C        H      N                                         ______________________________________                                        % calculated        69.45    6.32   22.51                                     % found             69.33    6.50   22.43                                     ______________________________________                                    

EXAMPLE 12 Preparation of1,2-dihydro-1-oxo-5,11-dimethyl-dipyrido-[4,3-b][3,4-f] indole (compoundof formula L: compound 26).

The general schema of the synthesis of this compound is shownhereinafter. This synthesis was carried out according to the proceeding(c) to obtain the compound of formula E (reactions 1 to 4) which is aparticular compound of general formula (12) and according to proceedingn°2 (reactions 5 to 11). Compound (G) to (L) hereinafter may bepresented in tautomeric form. ##STR17##

2,5-dimethyl-3-nitro-benzaldehyde (B)

The mixture constituted by 2,5-dimethyl-3-nitrobenzyl-chloride (A)prepared according to M. J. WINCHESTER and F. D. POPP, J. Het. Chem. 12,p. 547 (1975) (610 g), acetic acid (1280 ml, water (1280 ml) andhexamethylene tetramine (855 g) was heated with reflux under stirringfor 2 hours. 1037 ml of concentrated hydrochloric acid were then addedin 10 minutes and the mixture was again heated with reflux for 20minutes. This mixture, cooled to 0° C., gave a solid which was filteredoff, dried and recrystallised from cyclohexane (4 liters) to give 290.5g (53%) of yellow needles corresponding to the aldehyde of formula B,melting point : =90°-93° C.

    ______________________________________                                        Analysis: C.sub.9 H.sub.9 NO.sub.3 = 179                                                      C        H         N                                          ______________________________________                                        % calculated    60.30    5.06      7.80                                       % found         60.13    4.97      7.71                                        ##STR18##                                                                    ______________________________________                                    

2,5-dimethyl-3-nitro-trans cinnamic acid (C)

The mixture constituted by 193.7 g of aldehyde of formula B,112.5 g ofmalonic acid, 1.5 1 of pyridine dried on potassium hydroxide and 9 ml ofpiperidine was heated with reflux for 24 hours but adding, twice, 112.5of malonic acid, after 31/2 hours and 6 hours of reflux. Afterevaporation of the solvent, the residue was taken up with acetone,filtered off, washed in water and again in acetone to give the purecompound C, which was recrystallised from ethanol and gave ochremicro-crystals, melting point : 228° C. Yield: 173 g (72%).

    ______________________________________                                        Analysis: C.sub.11 H.sub.11 NO.sub.4 = 221.21                                                  C        H         N                                         ______________________________________                                        % calculated:    59.72    5.01      6.33                                      % found          59.74    4.91      6.21                                       ##STR19##                                                                     ##STR20##                                                                    ______________________________________                                    

2,5-dimethyl-3-acetylamino-trans cinnamic acid (E)

141 g of nitrocinnamic acid of formula C were suspended in 1260 ml ofacetic acid; 170 g of Raney nickel washed in acetic acid and hydrogenwere added to this mixture, the mixture being stirred in a hydrogenatmosphere under normal pressure until cessation of absorption of saidhydrogen. (The theoretical quantity was absorbed). Hot filtration waseffected to eliminate the catalyst and half of the acetic acid wasevaporated.

A small sample was evaporated to dryness, taken up with water,neutralised in ammonia, filtered off and recrystallised from ethanol toobtain colourless microcrystals corresponding to2,5-dimethyl-3-amino-trans cinnamic acid of formula D, melting point185° C.

    ______________________________________                                        Analysis: C.sub.11 H.sub.13 NO.sub.2, 1/2 H.sub.2 O = 200.23                                       C       H      N                                         ______________________________________                                        % calculated:        65.98   7.05   7.00                                      % found              65.62   6.82   7.07                                      ______________________________________                                    

To the rest, coming from the evaporation of half of the acetic acid, 150ml of acetic anhydride were added, the resulting mixture was heated withreflux for 11/2 hours then evaporated to dryness. The solid residue wastaken up with hydrochloric water, stirred for 1 hour and filtered off togive a solid which was recrystallised from acetic acid, giving 126.2 g(84%) of colourless flakes corresponding to the acid of formula E,melting point 270° C.

    ______________________________________                                        Analysis: C.sub.13 H.sub.15 NO.sub.3 = 233                                                    C        H         N                                          ______________________________________                                        % calculated    66.93    6.48      6.01                                       % found         66.78    6.51      6.11                                        ##STR21##                                                                    ______________________________________                                    

2,5-dimethyl-3-acetylamino-trans cinnamoylazide (F)

The mixture formed by 125 g of cinnamic acid E, 1.1 liter of acetone and54 g of triethylamine was cooled up to 0° C., then 78.8 g ofethyl-chloroformate dissolved in 460 ml of acetone were progressivelyadded with stirring and maintaining the temperature at 0° C. Stirringwas continued for one hour at 0° and in continuing to cool to maintainthe temperature below 5° C., a solution of 52.5 g of sodium azide in theminimum of water was added. After the end of the addition, stirring wasagain effected for 1 hour at 0° C., the mixture was allowed to return toambient temperature, then poured in 5 l of water and the precipitateformed was filtered off. This latter was washed abundantly in water, interminating the washing with distilled water, then with a little acetoneand finally dried to obtain 107 g (77%) of fine cottony needles whichmelt from 150° C. and present one stain only in thin layerchromatography on silica gel. This compound F is used as such in thefollowing synthesis. ##STR22##

1,2-dihydro-1-oxo-5,8-dimethyl-6-acetylamino-isoquinoline(G)

To the mixture constituted by 500 ml of diphenylether and 28.6 g oftributylamine heated at 240° C. and maintained under violent stirring,were progressively added, in 15 minutes, 39.6 g of azide in suspensionin 450 ml of diphenylether maintained at 40° C., care being taken thatthe temperature does not drop below 235° C. After the end of theaddition, stirring was effected for a further 15 minutes at 240° C. thenthe mixture is allowed to cool, eliminating part of the diphenyl etherunder vacuum. The crystallisation of a solid was observed, 350 ml ofbenzene were added and the precipitate was filtered off. Said latter wastaken up with 400 ml of boiling ethanol and the insoluble fraction,filtered off, was recrystallised from 400 ml of dimethylformamide,unfiltering hot, to obtain 18.7 g (53%) of colourless flakescorresponding to compound G.

    ______________________________________                                        Analysis: C.sub.13 H.sub.14 N.sub.2 O.sub.2 : 230.3                                           C        H         N                                          ______________________________________                                        % calculated    67.80    6.13      12.17                                      % found         67.54    6.42      11.96                                       ##STR23##                                                                    ______________________________________                                    

1,2-dihydro-1-oxo-5,8-dimethyl-6-amino-isoquinoline (H)

The mixture consisting of 10.6 g of the compound G, 175 ml of ethanoland 35 ml of concentrated hydrochloric acid was heated with reflux for21/2 hours, 300 ml of water were added, the mixture was again heated toboiling point and filtered to eliminate a small insoluble fraction. Tothe cooled filtrate was added a N sodium hydroxide solution to bring thepH to 9 and the precipitate formed was filtered off then recrystallisedfrom ethanol to give 7.35 g (85%) of cream flakes corresponding to theamine of formula H, melting point 242° C.

    ______________________________________                                        Analysis: C.sub.11 H.sub.12 N.sub.2 O = 188.2                                                  C        H        N                                          ______________________________________                                        % calculated     70.18    6.43     14.88                                      % found          70.25    6.15     14.52                                       ##STR24##                                                                     ##STR25##                                                                    ______________________________________                                    

1,2-dihydro-1-oxo-5,8-dimethyl-6-[4'-(3'-nitro-pyridyl) amino]isoquinoline or 5,8-dimethyl-6-[4'-(3'-nitropyridyl)amino] isoquinoline(I)

The mixture consisting of 34.7 g of the amine of formula H, 27.3 g of3-nitro-4-chloro-pyridine and 1 liter of dimethylformamide was stirredat ambient temperature for 15 days and the solvent was evaporated. Theresidue was taken up with 3 liters of N hydrochloric acid and theinsoluble fraction was filtered off. It corresponds essentially to anundesirable secondary compound which recrystallised fromdimethylsulfoxide in form of orange-red micro-crystals, non melting at300° C.

    ______________________________________                                        Analysis: C.sub.27 H.sub.23 N.sub.5 O.sub.4,H.sub.2 O = 499.5                                     C        H      N                                         ______________________________________                                        % calculated        64.92    5.04   14.02                                     % found             65.19    4.81   13.79                                     ______________________________________                                    

To the aqueous phase was added a N sodium hydroxide solution to bringthe pH to 9-10 and the precipitate formed was filtered off, thenrecrystallised from dimethylformamide to give 22 g (39%) of yellowmicro-crystals corresponding to the compound of formula I, melting point310°-315° C.

    ______________________________________                                        Analysis: C.sub.16 H.sub.14 N.sub.4 O.sub.3 = 310.3                                            C        H         N                                         ______________________________________                                        % calculated     61.93    4.55      18.06                                     % found          61.53    4.71      17.76                                      ##STR26##                                                                     ##STR27##                                                                    ______________________________________                                    

1,2-dihydro-1-oxo-5,8-dimethyl 6-[4'-(3'-amino-pyridyl)amino]isoquinoline J and1-[6'-(14,2'-dihydro-1'-oxo-5',8'-dimethylisoquinolyl)] triazolo(4,5 c)pyridine (K)

To 16.8 g of nitrated derivative I in 1 liter of acetic acid were added17 g of Raney nickel and hydrogen, stirring the whole under a hydrogenatmosphere at ambient temperature and at normal pressure. Thetheoretical quantity of hydrogen was absorbed in about 1 hour and thecatalyst was filtered, then 50 ml of the resultant solution were taken.

By evaporating this solution, a residue was obtained which was taken upwith water and rendered alkaline by the addition of a N-sodium hydroxidesolution. The precipitate formed was filtered off, it was recrystallisedfrom acetonitrile, then from anisole to obtain colourless micro-crystalscorresponding to the amine of formula J, melting point 212°-215° C.

    ______________________________________                                        Analysis: C.sub.16 H.sub.16 N.sub.4 O, H.sub.2 O = 298                                          C         H      N                                          ______________________________________                                        % calculated      64.41     6.08   18.78                                      % found           64.14     5.83   18.83                                      ______________________________________                                    

The remaining solution was cooled to 14° C. and, with stirring, asolution of 3.61 g of sodium nitrite in the minimum of water was addedwith 15 minutes. Stirring was continued for 11/2 hours, allowing themixture to return to ambient temperature, the solvent was eliminated,the residue was taken up with water, filtered off and the precipitatewashed in water. The solid obtained was taken up with 1.5 l of boilingethanol, filtering was effected, then concentration to 600 ml to give,after cooling, 12g (80%) of cream microcrystals corresponding to thetriazolopyridine of formula K, melting point 300°-302° C.

    ______________________________________                                        Analysis: C.sub.16 H.sub.13 N.sub.5 O = 291                                                   C        H         N                                          ______________________________________                                        % calculated    65.97    4.5       24.04                                      % found         65.66    4.70      24.39                                       ##STR28##                                                                    ______________________________________                                    

1,2-dihydro-1-oxo-5,11-dimethyl-dipyrido-[4,3-b][3,4-f] indole L

16g of triazolopyridine of formula K were mixed with 80 g ofphenanthrene, and in maintaining the whole under stirring, the mixturewas heated in a metal bath at 340° C. for 30 minutes, after which timethe emission of nitrogen substantially stopped. Heating was theneffected at 360° C. for 2 minutes, the mixture was allowed to cool andpoured in 600 ml of hexane. The insoluble precipitate was filtered off,washed in boiling hexane, then recrystallised from dimethylformamide togive 5.7g (36.5%) of grey needles, non-melting at 330° C.

    ______________________________________                                        Analysis: C.sub.16 H.sub.13 N.sub.3 O 1/2 H.sub.2 O: 272.3                                       C          H      N                                        ______________________________________                                        % calculated       70.57      5.18   15.43                                    % found            70.63      5.32   15.22                                    ______________________________________                                    

EXAMPLE 13

This example illustrates the proceeding (b) for obtaining the compoundof formula (12) in which R'₂ is hydrogen, i.e. the compound of formula(12a) hereinafter, ##STR29##

2-methyl-3-nitro-trans cinnamic acid (32a)

In a 1 liter, 3-necked flask were introduced 15.2g of 2-methyl-3-nitroaniline (30a) which were dissolved in 200 ml of acetone and 17 ml ofconcentrated hydrochloric acid were added, then the whole was cooled to0° C.

By maintaining the solution below 5° C., and with stirring,diazotisation was effected by progressively adding a solution of 7.5g ofsodium nitrite in 25 ml of water.

After having left the preceding solution with stirring for 30 minutes,it was poured slowly into a 3-necked flask containing a mixtureconsisting of 100 ml of acrylic acid, 7.6g of cupric chloride dissolvedin 25 ml of water and 100 ml of acetone, the whole being maintained at atemperature of 35° C. for the whole duration of the addition which lastsfrom 15 to 25 minutes.

This new mixture was maintained with stirring at 35° C. for one hourthan the acetone and the excess of acrylic acid were evaporated. Theresidue was taken up with chloroform, washed in water and the chloroformphase was exhausted with a cold 2N sodium hydroxide solution (twice 50ml). By acidification with hydrochloric acid, the(2-methyl-3-nitro-phenyl)-chloro-propionic acid (31a) was precipitated,filtered off and dried.

The latter was entirely treated by heating it with reflux for 30 minutesin 100 ml of methanol containing 10 g of potassium hydroxide and, afterevaporation, the residue was taken up with water and acidified in thecold by hydrochloric acid. The precipitate was filtered, dried andrecrystallised from xylene to give 2-methyl-3-nitro-cinnamic acid (32c),melting point 222° C.

Yield (with respect to the amine used):11.9g (57.5%). ##STR30##

2-methyl-3-acetylamino-trans cinnamic acid (12a)

In a 2-litre 3-necked flask, 84.5g of nitro-acid (32a) were dissolved in750 ml of acetic acid, 100g of commercially available Raney nickelwashed with acetic acid and hydrogen were added, stirring being effectedunder a hydrogen atmosphere at normal pressure and at ambienttemperature.

Hydrogenation was stopped when the volume of hydrogen consumed exceededthe theoretical volume (28.4 l instead of the necessary 27.4) or after 4hours 25 minutes stirring.

The catalyst was filtered off, was washed with acetic acid and half ofthe solvent was evaporated. 90 ml of acetic anhydride were then addedand the mixture was heated with reflux for 11/2 hours then evaporated todryness.

The residue was taken up with 500 ml of boiling acetic acid, filteringwas carried out in the hot to eliminate the insoluble Ni salts and, oncooling, 44 g of the expected acid were obtained.

By concentration of the mother liquors, about 10 g of the desiredcompound (12a) were further recovered, melting point 265°-267° C. Thetotal yield was a minimum of 54g (60.2%).

PHARMACOLOGICAL TESTS

The following tests were made in groups of 10 mice, unless stipulated tothe contrary.

Test 1: Study of the antitumoral properties of the compounds of theinvention of L 1210 leukemia

The antitumoral properties of the compounds according to the inventionwere determined by their curative action on test inoculated L 1210leukemia.

This leukemia was maintained on CBD 1(C 57 B 16×DBA/2) Fl mice. Thecompounds to be tested were injected by the IP route one or more daysafter the inoculation of the cells (single injection). The resultsobtained, shown in table I hereinafter, are expressed in percentage ofincrease of life span (ILS %) and in percentage of the number of cellskilled by the compound to be tested, the survival of the animals beingproportional to the number of cells injected.

The percentage of the like span ILS % (Cancer. Res. 1971, 31, 1883-1887)is the following ratio: ##EQU1##

The results of table I show that the products according to the inventionpossess antitumoral properties.

Test 2: Viro-induced Leukemia: Friend leukemia

The protective power of the compounds according to the invention wassought on Friend leukemia, inoculated into DBA2 mice aged from 5-6weeks. The viral inoculum was produced from a homogenate of leukemicspleen (p/volume) diluted to 1/250 in isotonic phosphate buffer withoutCa⁺⁺ nor Mg⁺⁺ (PBS), corresponding to 100 SD 50 (i.e. to the dose ofvirus which induces a splenomegaly in 50% of the inoculated mice).

The virus was injected by the IP route and in a volume of 0.2 in ml. Theproduct to be tested was injected 5 hours after the virus or 1 day afterthe virus at the dose indicated in a volume of 0.1 ml (IP route). Eachgroup of twenty control mice received the virus and a placebo or theproduct to be tested, 10 mice were sacrified on the 21st day, and theirspleen removed and weighted. The mice were considered as leukemic whenthe weight of their spleen exceed 200 mg. For the 10 mice, the life spanof the animals was determined.

The results obtained are shown in table II. These results show thatthese products possess an antiviral activity in addition to theirantitumoral activity.

Test 3: Study of the development of the viro-induced Moloney sarcoma

The injection of Moloney virus [C. Jasmin et al. J. Nat. Cancer Inst.1974 53 469-474] by the intramuscular i.m.route into new-born mice ledafter 10 days to the formation of a sarcoma. The appearance of thetumour was proportional to the dose of virus injected. The viralinoculum was constituted by a tumour homogenate diluted to 1/250, thiscorresponding to 10 TID 50, i.e. to the dose of virus inducing theappearance of a tumour in 50% of the animals infected. At this dose, 80to 100% of the animals developed a tumour, and 100% of the survivorsbecame leukemic. The experiment thus consisted in noting the number ofmice presenting tumours, the regression, or not, of these tumours andfinally in sacrificing the surviving animals after 2 months and innoting the presence or absence of splenomegaly (evidence of a leukemia).The virus was inoculated into new-born mice of 3 to 5 days by the IMroute, and the mice received the following day (J+1) or five hours afterinjection (JO+5 hours) the product to be tested by the IP route. Theresults obtained are as follows:

Controls virus:

80% of the young mice presented tumours

10% of the tumours regressed

30% of the animals survived and all presented a leukemia.

Compound of example 7:injection on J+1; 1 μg/mouse (0.5mg/kg)

70% of the mice presented tumours

90% of the tumours regressed

90% of the animals survived

0% presented a leukemia.

HUM : injection on J+1; 5 μg/mouse (2.5 mg/kg)

20% of the animals present a tumour

100% regression

10% of the mice were leukemic.

HUM: injection on J+1, 1 μg/mouse (0.5 mg/kg)

30% of the animals present a tumour

90% regression

90% survivors

33% were leukemic.

Controls virus:

90% of the animals present a tumour

40% of the tumours regressed

90% of the mice survived

45% of the mice were leukemic.

Compound of example 7: injection on JO+5 hours; 1 μg/mouse (0.5 mg/kg).

5% of the animals present a tumour

100% regressed

100% survived

40% present a leukemia.

Compound of example 1: injection on JO+5 hours; 1μg/mouse (0.5 mg/kg)

50% of the animals present a tumour

30% regressed

75% survived

65% are leukemic. Test 4: Investigation of the toxicity

The toxic dose has been sought, on adult (C 57,BL 6×DBA/2) Fl mice andon new-born mice, of the compounds of the invention by injection byinjection by the IP route. The results obtained are given hereinafter:

1- On adult Fl mice (C 57 BL 6×DBA/2)Fl (IP route)

(a) Compound of example 1:

Injectioni of

2 mg/mouse (80 mg/kg)=5 dead /6

1 mg/mouse (40 mg/kg)=1 dead/8

9.5 mg/mouse (20 mg/kg)=1 dead/6

(b) Compound of example 7:

Injection of

1 mg/mouse (50 mg/kg)=1 dead/3

0.6 mg/mouse (30 mg/kg)=5 dead/10

0.5 mg/mouse (25 mg/kg) 0 dead/5

0.3 mg/mouse (15 mg/kg)=0 dead/6

The LD₅₀ of the compound of example 7 is therefore 30 mg/kg.

2-On new-born mice (IP route)

5 μg: 2.5 mg/kg=3 dead/8, mice puny in appearance

HUM 10 μg: 5 mg/kg=3 dead/8, mice puny in appearance.

These results show that the toxic dose of the compound of example 7 ishigher than 2.5 mg/kg of mouse.

Test 5- Cytotoxic effect in vitro

The cytotoxic efforts of the compounds according to the invention weretested in vitro on cultures of hamster, human and mouse cells.

In particular, the BHK21 strain of hamster cells and a clone derivedfrom this strain transformed by Hamster Sarcoma Virus (HS5 clone) wereused.

After detachment by trypsine, the cells were seeded in plastic Petridishes (35 mm diameter) at the concentration of 2.10⁵ cells/dish, inEagle medium supplemented with "Bactotryptophosphate" Broth, Difco and10% calf serum (R. M. STOKER and I. MACPHERSON Virology 14, 1961, 359).

5 hours later, the cells were well attached to the plastic support, andthe products to be tested were added, dilutions having been made thereofin water or in DMSO (dimethylsulfoxide) if the product is sparinglysoluble in water. In this latter case, a control was made with the samefinal concentration of DMSO in the culture medium.

The state of the cells was examined 24, 48 and 72 hours afterwards.

The results (table III) clearly show that the products are clearlycytotoxic at concentrations from 0.2 to 10 μm, and that the most activeproduct, i.e. the compound of example 7, is ust as active as the alreadyknown derivatives, 2-methyl-9-hydroxy-ellipticinium acetate and9-hydroxy-ellipticine.

The effects on the two types of cells, normal and transformed, aresimilar.

Test 6: Action on the macromolecular syntheses

The action of the compounds according to the invention was studied bythe incorporation of precursors marked by radioactive isotopes:

¹⁴ C methyl-thymidine for studying the DNA synthesis

³ H5 for that of the RNA

³ Hv valine for that of the proteins.

These precursors were given for a period of 30 minutes at varying timesafter the addition of the product to be tested.

The incorporation is measured after lysis of the cells for 1% of sodiumdodecylsulfate and precipitation by 5% of trichloroacetic acid. Theacidosoluble precipitate was collected on glass fibre Whatman GF/Afilters. The filters were dried and counted in a liquid scintillationspectrometre.

Table IV gives the typical results for the compound of example 1:5,11-dimethyl-dipyrido-[4,3-b][3,4-f]indole.

It is ascertained that this compound reduces very rapidly, in the hoursfollowing its addition, the DNA and RNA syntheses and, to a lesserdegree, the synthesis of the proteins.

Experiments made on synchronised cells (G. TORFIER, J. GRUEST & L.MONTAGNIER Experimental Cell Research 85, 1974, 437) have shown that thecompound of example 1 stops, in the first minutes following itsaddition, the replication of the DNA, both at its initiation andelongation steps.

Test 7: Study of the antitumoral activity in vitro

This activity was measured on a tumoral strain derived from the murineleukemia due to the C. FRIEND virus.

The tumoral cells multiply in suspension in a "RPMI 1640" medium(Catalogue of GIBCO Bio-cult. Ltd, Washington Road, Sandyford IndustrialEstate, PAISLEY PA 3 4EP, Renfrewshire, Scotland) supplemented with 20%of embryonary calf serum, penicillin and streptomycine. The duplicationtime of these cells is 11 hours. The growth fraction is equal to 1 orvery close to 1 (all the cells are in the cycle). The cultures aresub-cultured at time t=0 at the concentration of 2.10⁵ cells per ml inFalcon dishes containing 4 ml of medium. After twenty four hours, theproduct to be tested was added, i.e. at a moment when the cultures arein exponential phase of growth. Twenty four hours after the addition ofthe product, the cells are counted and the precentages of living cellsdetermined by an exclusion test using "trypan" blue. Two dises maytherefore be defined:

    ______________________________________                                        (1) LD 50                                                                     (2) LD 100                                                                                                 Activity*:                                                     LD 100                                                                               LD 50                                                                                  ##STR31##                                       ______________________________________                                        Reference product:                                                            9-hydroxy-ellipticinium                                                       acetomethylate 7 10.sup.-7                                                                            3 10.sup.-7                                                                            1                                            compound of example 1                                                                        5 10.sup.-7                                                                            10.sup.-7                                                                              3                                            compound of example 2                                                                        5 10.sup.-6                                                                            1.5 10.sup.-6                                                                          0.2                                          compound of example 5                                                                        6 10.sup.-6                                                                            2 10.sup.-6                                                                            0.15                                         compound of example 6                                                                        5 10.sup.-6                                                                            10.sup.-6                                                                              0.3                                          compound of example 7                                                                        5 10.sup.-8                                                                            10.sup.-8                                                                              20                                           ______________________________________                                         *Activity: This figure (ratio of the LD.sub.50 of HUM with respect to the     LD.sub.50 of the product lobe tested) is quite arbitrary and gives an ide     of the activities of the different products by comparing them with the        HUM, the most active product in the series of the ellipticines.          

Test 8: Acute toxicity in vivo

The products to be tested were injected by the IP route into groups of10 mice at various dilutions. Each day, the number of dead animals isnoted. If the doses are well chosen, a 100% lethal dose and a 50% lethaldose have been able to defined for each product. This study is limitedto two months. Two isogenic mouse strains were systematically used:C3H/He and ICFW.

    ______________________________________                                                    Mouse strain                                                                           LD 100    LD 50                                          ______________________________________                                        Compound of example 1                                                                       C3H        200 mg/kg 100 mg/kg                                                ICFW       200 mg/kg 150 mg/kg                                  compound of example 7                                                                       C3H         35 mg/kg  20 mg/kg                                                ICFW        25 mg/kg  15 mg/kg                                  ______________________________________                                    

Test 9: Action on chloromonocytary tumoral cells

In this test, the action of the products according to the invention onchloromonocytary tumoral cells was determined according to thechloroleukemia of the mouse test (ICFW mouse, co-sanguine CFW strain)isolated in Unit 22 (B. TAMBOURIN and F. WENDLING) of the "InstitutNational de la Sante et de la Recherche Medicale--Paris" (I.N.S.E.R.M.)in a mouse injected with a variant of the Friend virus.

The tumour kills all the animals injected in 19.3± 2 days. This tumourdevelops in semi-solid ascitic form; the peritoneum is invaded, both bysolid tumoral masses and cells in suspension in the ascitic liquid. Thetumour is transmitted by the cells of the suspension which produce thetumoral masses and the ascitic cells.

    ______________________________________                                                    Mean        Mean survival                                                     survival time                                                                             time after                                                        without treatment                                                                         treatment                                             ______________________________________                                        Compound of formula 8                                                         (40 mg/kg 6 hours after                                                                      18.5 ± 2 days                                                                           25.3 ± 3.1 days                                inoculation)                                                                  Compound 21 (1 mg/kg                                                          24 hours after inoculation)                                                                  18.9 ± 1.8 day                                                                          29.0 ± 3.0 days                                ______________________________________                                    

Test 10- Comparison of the antitumoral activity of the compoundaccording to example 7 with that of known products

The compound of example 7, i.e.1-(γ-diethylaminopropyl)amino-5-methyl-dipyrido-[4,3-b][3,4-f] indole orknown compounds were injected into L 1210 leukemic mice 1 or 3 daysafter the inoculation of the cells at the doses indicated in tables V toVII and the mean survival time (MST) and the percentage of increasedlife span (ILS %) were measured.

Indications concerning the known products used in this example andparticularly their antitumoral properties, their secondary effects andtheir use in man may be found in "La Chimiotherapie des Cancers", by G.MATHE and M. KENIS Expansion Scientifique Francaise, 3rd edition, Paris1975.

Test 11

L 1210 leukemic mice were injected with the compound of example 8(compound 22), i.e. 1-(γ-dimethylaminopropyl)amino-5-methyl-dipyrido[4,3-b][3,4-f] indole, one day after the inoculation of the cells (dayJ + 1) at the doses indicated in table VIII and the mean survival time(MST) and the increase in life span (ILS %) were measured.

This test was carried out with 10³, 10⁴ and 10⁵ leukemic cells on day J.This test was also carried out with the compound of example 7, i.e.1-[(γ-diethylaminopropyl)amino]-5-methyl-dipyrido [4,3-b][3,4-f] indole(compound 21).

The results obtained are indicated in table VIII. This table also showsthe number of the surviving mice; a mouse is considered as survivor ifit has survived at least 2 to 3 months after the inoculation of theleukemic cells.

Test 12- Study of the protection of the leukemic mice inoculated L 1210cells) by a single dose or a fractioned dose.

The compound of example 7, i.e.1-[(γ-diethylaminopropyl)amino]-5-methyl-dipyrido [4,3-b][3,4-f] indolewas injected into L 1210 leukemic mice by one injection (10 mg/kg at dayJ + 3) or by fractioned doses (2.5 mg/kg each injection on days J + 3,J + 4, J + 5 and J + 6).

The results in table IX show that a single dose has greater antitumoralactivity than the same dose injected on 4 occasions.

Test 13- Lewis carcinoma

For this test, reference may be made to the following works:

"carcinome pulmonaire de Lewis" (3LL), K. SUGIURA and C. C. STOCK",Cancer Res. 1955 15 38-51.

La Chimiotherapie des cancers by G. MATHE and Y. KENIS, ExpansionScientifique Francaise, 3rd edition, Paris 1975. S. A. SCHEPARTZScreening, 1971, Cancer Chemiother. Rep. Part 3 vol. 2, page 3.

In this test, cells (10⁶ cells) removed from a tumour-carrying mousewere injected into mice (BDF₁) by the IM route. The mice developed, 10to 15 days after the inoculation, a tumour at the spot where theinjection was made. On the other hand, these cells made metastasis inthe lung, forming colonies on the pulmonary surface. The antitumoral andantimetastasic effect of a product may therefore be judged on mice thustreated.

Investigation of the antimetastasic effect of the compounds of examples7 and 8 of the invention

10⁶ cells taken from a tumour-carrying mouse were injected by the IMroute (left-hand paw) into groups of 10 mice and the compounds to betested were inoculated by the IP route on day J + 5 by single orfractioned injection. The mean survival time (MST) and the increasedlife span (ILS %) were determined.

    ______________________________________                                                    Number of injections                                                                        MST    ILS                                          ______________________________________                                        non-treated controls          25                                              Mice treated with the                                                                       4 injections    27.4   9.6                                      compound of example 7                                                                       J + 5 + 6 + 10 + 11                                                           2.5 mg/kg each                                                  Mice treated with the                                                                       1 injection                                                     compound of example 7                                                                       J + 5           32.7   30.8                                     Mice treated with the                                                                       10 mg/kg                                                        compound of example 8                                                                       J + 5           27.44  9.8                                                    5 mg/kg                                                         ______________________________________                                    

It may be concluded that the compounds of examples 7 and 8 give aprotective action concerning the metastasic pulmonary invasion of thelung. In fact, one treated mouse and one non-treated mouse weresacrified on day J + 22 and the pulmonary metastases counted: 77metastases were counted in the non-treated mouse and 35 in the mousetreated on day J + 5 (one injection) with the compound of example 7.

Test 14: viro-induced leukemia: Friend leukemia

(A) As in test 2 hereinabove, the Friend leukemia virus inoculum wasobtained from leukemia spleen and diluted to contain 100 SD₅₀ /0.2 ml(SD₅₀ =spleen enlarging dose 50 percent). The product to be tested wascompound 21 (obtained according to example 7). It was given by I. P.route as a single injection 1 day after virus inoculation.

The results obtained are indicated in table Xa. Treatment with thiscompound 21 as well as with compound of example 1 (see table II)resulted in a significant increase of the life span.

Half of the mice treated with compound of example 1 according to test 2or with compound 21 as above explained were sacrificed 21 days aftervirus incoulation, their spleen removed and weighted. The mean spleenweight for the control mice was 2,520 mg (1,919-2,866), that of micetreated with 5 mg/kg of compound of example 1 was 2,013 mg (887-2,793),with 25 mg/kg 1,803 (718-2,635) and with 50 mg/kg 960 (373-1,230). Formice inoculated with compound 21 1 day after the virus, the mean spleenweight was 1,935 mg (500-2,950). The decrease of the splenomegaly is inline with the increase of the life span and suggests that the compoundsact also as antiviral agents in this system.

                  TABLE Xa                                                        ______________________________________                                        Action of compound 21 on Friend leukemia                                                        Range of death                                                      Drug (mg/kg)                                                                            (in days)   MST    ILS %                                    ______________________________________                                        Control mice                                                                            0           20-56       32                                          mice treated                                                                  with compound                                                                 21 (ex.7) 5           27-52       44.5 39                                     ______________________________________                                    

(B). The proceeding of test 2 was repeated by using the compound 21 i.e.1-[(γ-diethylaminopropyl)amino]-5-methyl-dipyrido [4,3-b][3,4-f] indoleobtained according to example 7.

This test was carried out with a single dose of compound 21 (20 mg/kg)and with various virus doses.

The results obtained are shown in table Xb.

                  TABLE Xb                                                        ______________________________________                                        Viro induced leukemia: Friend leukemia                                        Compound 21: single dosage: 20 mg/kg                                          various dosages of virus                                                                                        Survivors 4                                        Range of                   months after                                       death.sup.(1)                                                                         MST.sup.(2)                                                                            ILS %.sup.(3)                                                                           inoculation                                 ______________________________________                                        Controls                                                                      virus 1/500                                                                            24-38     29.1     --      0                                         (1000 SD.sub.50)                                                              Compound 21                                                                            31-51     40.7     40      0                                         J + 1                                                                         Controls                                                                      virus 1/2000                                                                           25-44     33.8     --      0                                         (250 SD.sub.50)                                                               Compound 21                                                                            50-82     55.4     64      2                                         J + 1                                                                         Controls                                                                      (virus 1/1000)                                                                         18-36     24.3     --      0                                         Compound 21                                                                   J + 1    30-54     44.4     82.7    0                                         ______________________________________                                         .sup.(1) Range of death: the first figure indicates the date when the         first mice died and the second the date when the latter mice died             .sup.(2) MST: Mean of survival time                                           .sup.(3) ILS % (increased life span) = increase of the life time; it take     care of dead animals                                                          ##STR32##                                                                     MST.sub.t = treated animals; MST.sub.c = control animals                 

Test 15: L 1210 Leukemia

The proceeding of test 1 was repeated with the compound of formula 8obtained according to example 1, i.e. 5,11-dimethyl-dipyrido[4,3-b][3,4-f]indole. In this test, the compound of formula 8 wasinjected four days after the inoculation of the cells (50 mg/kg). Theresults are shown in table XI wherein the results obtained with the samecompound injected one day after the cell inoculation are also reported(see experiment n° 2 in table I). The results show that the increasedlife span (ILS %) was higher when the product was given earlier afterthe cells inoculum.

                                      TABLE XI                                    __________________________________________________________________________    Cell               Dose                                                                              Day of                                                                              Range of                                                                           MST                                         number      Drug   mg/kg                                                                             inoculation*                                                                        death                                                                              (day)                                                                            ILS %                                    __________________________________________________________________________           10.sup.6                                                                           0      0   0      7-12                                                                              7.8                                                10.sup.6                                                                           compound of                                                                          50  + 1    9-15                                                                              11.5                                                                             47.3                                                 example 1                                                                10.sup.5                                                                           0      0   0      8-11                                                                              9.3                                         Exp.=2                                                                               10.sup.5                                                                           compound of                                                                          50  + 1   10-13                                                                              12.85                                                                            38.1                                                 example 1                                                                10.sup.4                                                                           0      0   0     10-13                                                                              11                                                 10.sup.4                                                                           compound of                                                                          50  + 1   11-14                                                                              12.3                                                                             11.8                                                 example 1                                                                10.sup.6                                                                           0      0   0     6-7  6.7                                                10.sup.6                                                                           compound of                                                                          50  + 4    8-13                                                                              9  34.3                                                 example 1                                                                10.sup.5                                                                           0          0      8-12                                                                              8.9                                         Exp=4                                                                                10.sup.5                                                                           compound of                                                                          50  + 4   10-11                                                                              10.3                                                                             15.7                                                 example 1                                                                10.sup.4                                                                           0      0   0     10-11                                                                              10.5                                               10.sup.4                                                                           compound of                                                                          50  + 4   10-16                                                                              12 14.7                                                 example 1                                                         __________________________________________________________________________     *The drug is administered 1 day (+ 1) or 4 days after the cells inoculum.     Compound of example 1 = dimethyl5,11 dipyrido [4,3b] [3,4-f] indole.     

Test 16: Relationship between structure and activity of various dipyridoindoles differing by the R'1 substitution.

The R'1 substitution at the 1 position seems to be very important forthe protective effect of the derivatives against L1210 tumor cellgrowth.

L1210 leukemia has been maintained by weekly passages on(C57B16×DBA/2)F1 mice. On day 0, mice were inoculated by I. P. routewith various numbers of L1210 ascitic tumor cells in volumes of 0.1 ml.Subsequently as indicated, drugs were administered in Ca⁺⁺ and Mg⁺⁺ freePBS solutions (Gibco) or in Mac Coy's medium (Gibco or MicrobiologicalAssociates).

The relationship between the size of leukemic cell inoculum given IP andthe host life span was determined in groups of 10 mice after inoculationof 10³ to 10⁶ cells in 0.1 ml of Mac Coy's medium. The decrease in theaverage of host life-span between each consecutive ten-fold increase insize of the leukemic cell inoculum was 2 days. According to the methodof calculation of Dombernowsky, the doubling time was 0.615 days.

If the R'1 substituting lateral chain is γ-diethylaminopropyl (compound21) or γ-dimethylaminopropyl (compound 22), these compounds have similaror higher antitumoral activity. As shown in table XII (compound 21) and(compound 22) compete favorably with Ellipticinium acetate (HUM)indicating that the pyrido-indole structure is more effective than thepyrido-carbazole nucleus (ellipticine).

                  TABLE XII                                                       ______________________________________                                                                 Day                                                                           of                                                                            inoc-                                                                              Range           60                              Cell             Dose    ula- of         ILS  day                             number Drug      mg/kg   tion death MST  %    surv.                           ______________________________________                                        10.sup.4                                                                             0         0        0   10-14 11.8 --   0                               10.sup.4                                                                             compound  5       +1   13-21 16.2 33.3 1                                      21                                                                     10.sup.4                                                                             compound  0.5     +1   11-15 13.54                                                                              11.5 0                                      21                                                                     10.sup.4                                                                             HUM       5       +1   14-20 14.9 22.6                                 10.sup.3                                                                             0         0        0   13-16 13.8 --   0                               10.sup.3                                                                             compound  5       +1   15-22 17   23.2 5                                      21                                                                     10.sup.3                                                                             compound  0.5     +1   14-20 16.2 17.4 3                                      21                                                                     10.sup.3                                                                             HUM       5       +1   14-20 16.86                                                                              22.15                                                                              3                               10.sup.4                                                                             0         0        0   10-12 10.9      0                               10.sup.4                                                                             compound  5       +1   14-21 18   65.1 1                                      21                                                                     10.sup.4                                                                             compound  5       +1   12-15 13.7 25.7 3                                      22                                                                     10.sup.4                                                                             compound  2.5     +1   10- 19                                                                              14.7 34.9 1                                      22                                                                     10.sup.5                                                                             0         0        0    8-14 9.05                                      10.sup.5                                                                             compound  5       +1   11-16 13.8 52.5 0                                      22                                                                     10.sup.4                                                                             0         0        0   10-13 11.2                                      10.sup.4                                                                             compound  20      +4   10-17 11.3 0.9  0                                      of the                                                                        example 2                                                              ______________________________________                                    

Test 17: Relationship between the length of the substituting chain andthe activity.

The importance of the substitution of R'1 on 1 position for theantitumoral activity of these compounds was demonstrated above. If onevaries the length of the lateral chain γ-diethylaminopropyl-amino 1 forthe compound 21 or γ-diethylamino-ethylamino 1 for compound 23, as shownin table XIII, both compounds are active against L1210 leukemia at thesame dosage. However compound 21 is less toxic (50 mg/kg for compound 21and 25 mg/kg for compound 23), it has a higher ILS% than compound 23 and1 mouse survived up to 60 days. These results indicate that thediethylaminopropylamino-1 substitution corresponds to the best length ofchain for the therapeutic action of the derivative. Increasing thelateral chain by (γ-methyl δ-diethylamino-butyl)amino 1 such as compound24, similar antitumoral effect is found, conforming that compound 21 isthe compound the most active on the mice.

                  TABLE XIII                                                      ______________________________________                                                                             Survivors                                       Day of  Range of        ILS   up to 60                                        inoculation                                                                           death    MST    %     days                                     ______________________________________                                        Control            8-9       8.8                                              Compound 21                                                                            + 1       12-18    14.9 69.2  1                                      Compound 23                                                                            + 1       11-18    14.6 65.2  0                                      Control            10-13    11.2                                              Compound 21                                                                            + 4       14-32    18.5 65.6  0                                      Compound 24                                                                            + 4       12-20    17.5  56.25                                                                              0                                      ______________________________________                                    

Test 18: Relationship between dose and L1210 antitumoral activity ofcompound 21

The dose response of the activity of compound 21 as shown with L1210leukemia according to test 1 is as follows:

At 5 mg/kg, the mean survival time (MST) is significantly increased(ILS=87 percent); at higher doses of compound 21, the MST is alwayssignificant increased (ILS=52 p.cent at 10 mg and 75 p.cent at 20 mg/kg)and some were surviving up to 60 days (10 p.cent of inoculated mice at10 mg and 20 p.cent at 20 mg per kg).

Test 19: Effect of the time of administration of compound 21

As shown in table XIV, a single injection of compound 21 increasedsignificantly the mean survival time when given as later as 6 days afterthe L1210 cells inoculation. The results confirm that compound 21 ismore effective when given earlier after the cells inoculation (ILS=56.4%at day + 2, 43% at day + 3 instead of 20.8% at day + 6 or 2% at day +7). The non-protective effect at day + 7 could be explained by the factthat some cells migrate through a compartment inaccessible to the drug(as postulated by J. B. Le Pecq for the 9-hydroxy-ellipticine).

                  TABLE XIV                                                       ______________________________________                                        Day of                               Estimated                                administration                                                                              Range of               number of                                **            death    MST     ILS % cells***                                 ______________________________________                                        Control           10-11    10.1                                               BD 40* + 2        15-17    15.8  56.4  10.sup.5                                      + 3        12-17    14.4  43.0  5.10.sup.5                                    + 4        10-14    12.4  22.8  10.sup.6                                      + 5        10-13    11.9  17.8  5.10.sup.6                                    + 6        10-14    12.2  20.8  10.sup.7                                      + 7        10-13    10.3   2.0  5.10.sup.7                             ______________________________________                                         *BD 40 is given I.P. at 0.1 ml containing 0.4 mg/mice (20 mg/kg)              **Day 0 is the day of inoculation of 10.sup.4 L1210 cells given I.P.          ***Evaluation of the number of leukemic cells by the mean of calculation      of the doubling time (according to P. Dombernowsky).                     

Test 20: Study of the combination of compound 21 with other drugs

An increase of protection of mice inoculated with Lewis lung carcinoma14 days before a low priming dose followed by a high challenge dose ofendoxan was reported by J. Millar 1978, tenth congress of chimiotherapy(1978) in press., G. A. Preasant Cancer vol. 40 1977 p. 987-993 for thetherapy of drug-resistant breast carcinoma used a combination ofendoxan, BCNU and Adriamycin the following day.

The results concerning similar experiments (breast carcinoma and Lewiscarcinoma) with compound 21 are discussed in table XV. A priming dose ofendoxan (100 mg/kg) was given 3 days after 10⁵ leukemic cells (20 mice).The following day, 10 mice received 0.1 ml of PBS (control mice) and 10mice received 20 mg/kg of compound 21. Increase in life span wassignificantly higher in mice receiving endoxan and compound 21 comparedto the mice with endoxan or compound 21 alone. The results listed intable XV suggested that compound 21 given one day after endoxan orendoxan-BCNU gave rise to a higher protection of mice than endoxan,endoxan + BCNU or compound 21 given alone. Taking as control mice theendoxan treated mice, the ILS% is 57 for endoxan + compound 21 treatedmice and 63 for endoxan + BCNU + compound 21 treated mice.

                  TABLE XV                                                        ______________________________________                                                Range of death                                                                            MST       ILS %                                           ______________________________________                                        Control   10-13         11.2      --                                          Endoxan   11-17         13.1      16.9                                        BD 40     14-32         18.5      65.2                                        Endoxan                                                                       BD 40     18-24         20.6      84                                          Endoxan                                                                       + BCNU    10-17         13.7      22.3                                        Endoxan                                                                       + BCNU    18-24         21.4      91                                          + BD 40                                                                       ______________________________________                                         BD 40 is given I. P. at day + 4 (20 mg/kg)                                    Endoxan is inoculated I.P. at day + 3 (100 mg/kg) and BCNU immediately        after endoxan (2 mg/kg).                                                      Day 0 is the day of inoculation of 10.sup.5 cells given I.P.             

Test 21 : Toxicity of compounds 21,22,23, and 24.

All drugs were dissolved in aqueous solutions adjusted at pH 5 withacetic acid and inoculated to the mice under a volume of 0.1 ml I.P.after dilution in Mac Coy's medium.

The toxicity of the drugs after intraperitoneal injection was estimatedfrom the mortality rate up to the 30th day. The minimal quantityresulting in 100% deaths was 50 mg/kg for compound24, 50 mg/kg forcompound 21 and for compound 22, 25 for compound 23. In general, thedeaths occured early after drug administration (4-6 days for compound24, 4-8 for compound 21, 3-5 for compound 22 and 4-6 for compound 23).

                                      TABLE I                                     __________________________________________________________________________    Study of the antitumoral properties of the compounds according to the         invention                                                                     on L 1210 leukemia                                                                           Number of                                                                           Quantity in                                                                              Number of                                                                           Number of                                              cells mg/mouse   cells cells Surviving                         Compound tested                                                                        Experiment                                                                          injected                                                                            (mg/kg)                                                                              ILS %                                                                             found killed                                                                              mice                              __________________________________________________________________________    Compound of                                                                            experiment                                                                          10.sup.6                                                                            1 mg/mouse                                                                           34,32                                                                             10.sup.5                                                                            90%   0                                 example 1                                                                              n° 1                                                                         10.sup.5     15,73                                                                             40,000                                                                              60%   0                                 (formula 8)                                                                            J + 2**                                                                             10.sup.4                                                                            (50mg/kg)                                                                            14,78                                                                             6,000 40%                                                    10.sup.3     3   800   20%   1/10                              Compound of                                                                            experiment                                                                          10.sup.6                                                                            1 mg/mouse                                                                           47,3                                                                              8000  99%                                     example 1                                                                              n° 2                                                                         10.sup.5                                                                            (50 mg/kg)                                                                           38,1                                                                              2000  98%                                     (formula 8)                                                                            J + 1**                                                                             10.sup.4     11,8                                                                              5000  50%                                     Compound of                                                                            experiment  0,1 mg/mouse                                                                         no significant difference                         example 1                                                                              n° 3 0,05 mg/                                                                             with the controls 10.sup.4 cells                  (formula 8)          mouse     10.sup.3 cells                                 Compound 20          0,1 mg/mouse                                                                         0,1 mg toxic and no difference                    (example 6)                 with the controls 10.sup.4 cells                                                 10.sup.3 cells                                 Compound 21                                                                            Product                                                                             10.sup.4                                                                            0.1 mg/mouse                                                                         33.3                                                                              60    99.94 1/10                              (example 7)                                                                            injected by (0.5 mg/kg)                                                       I.P. route  0.1 mg/mouse                                                                         11.5                                                                              10.sup.3                                                                            90                                               J + 1**     (5 mg/kg)                                                               10.sup.3                                                                            0.01 mg/mouse                                                                        17.4                                                                              80    92                                                           (0.5 mg/kg)                                                                   0.1 mg/mouse                                                                         23.2                                                                              40    96    5/10                                                   (5 mg/kg)                                                HUM*                 0.1 mg/mouse                                                                  (5 mg/kg)                                                         product                                                                             10.sup.4                                                                            0.1 mg.m                                                                             22.6                                                                              400   96    1/10                                       injected by (5 mg/kg)                                                         I.P. route                                                                    J + 1**                                                                             10.sup.3                                                                            0.1 mg 22.15                                                                             60    94    3/10                                                   (5 mg/kg)                                                __________________________________________________________________________     *HUM: 2N-methyl-9-hydroxy-ellipticinium acetate                               **J + 1 or J + 2: injection one or two days after inoculation f the cells

                                      TABLE II                                    __________________________________________________________________________    Viro-induced leukemia - Friend leukemia                                                    Product to be                                                                        Mean survival time**                                                                     ***ILS                                                                            Weight of the spleens                      Mouse                                                                              Virus   tested Days       %   on the 21st day in mg                      __________________________________________________________________________    control                                                                            *VFA 1/250 (1)                                                                        --     31.7 (26-47)   2519 mg                                         VFA 1/250 (2)                                                                         --     28 (14- 17)    (2866-1919)                                Treated                                                                            VFA 1/250                                                                             compound of                                                                   example 1                                                                     (formula 8)                                                                   5hrs after the                                                                virus                                                                         0.1    47.6 (26-78)                                                                             59.5                                                                              2013 mg                                                                       (887-2793)                                              0.5    34.2 (22.54)                                                                             14.6                                                                              (1803 mg)                                                                     (718-2635)                                              1 mg   41.7 (14-81)                                                                             39.7                                                                              959,6 mg                                                                      (373-1230)                                 __________________________________________________________________________     Male DBAZ mice aged 5-6 weeks                                                 Experiment of 4.8.76:                                                         *VFA: anaemic Friend virus injected by the I.P. route, 0,2 ml dilution        1/250  100 SD 50                                                              **Mean survival time between brackets, dates on which the first and last      mouse died                                                                    ***Increase in the life span per 100                                     

                  TABLE III                                                       ______________________________________                                        Minimum dose involving complete inhibition of growth                                 Com-    Com-     Com-   Com-  Com-                                            pound   pound    pound  pound pound                                           exam-   exam-    exam-  exam- exam-                                           ple     ple      ple    ple   ple                                      Cells  1       2        5      6     7     HE*                                ______________________________________                                        C13/8  0.5 M   2        5      2     0.25  0.25                               HS 5   0.5 M   2        5      2     0.25  0.25                               ______________________________________                                         *HE = 9OH-hydroxy-ellipticine or 2acetomethylate-9-hydroxy-ellipticinium 

                  TABLE IV                                                        ______________________________________                                        Inhibition of the macromolecular syntheses by the compound                    of example 1                                                                                                    Incorporation                               Time, in hours,                                                                         Incorporation in                                                                          Incorporation                                                                             in proteins                                 of marking                                                                              the DNA (in %                                                                             in the RNA (in                                                                            (in % of the                                after addition                                                                          of the non- % of the non                                                                              non treated                                 of the product                                                                          treated control)                                                                          treated control)                                                                          control                                     ______________________________________                                        0.5       41          33          40                                          3         14          13          37                                          6         6.3         3.7         16                                          9         6           9           17                                          24        4           31          17                                          ______________________________________                                          the concentration of the product is 5 M                                       the cells HS5 were seeded 24 hours beforehand at a concentration of          5.10.sup.5 per Petri dish of 60 mm.                                      

                  TABLE V                                                         ______________________________________                                                         Quantity                                                     Compound In-     per                                                          tested   jection mouse    Range of death                                                                          MTS  ILS %                                ______________________________________                                        Control 10.sup.4          10-15 days                                                                              11                                        cells                                                                         Compound of                                                                            J + 1   0.2 mg   6-1 mouse alive on 30th day                         example 7                                                                     Compound of                                                                   example 7                                                                              J + 3   0.2 mg   11-17     13.8 25.45                                Thiotepa J + 3   0.1 mg   10-11     11   0                                    Mitomycine                                                                             J + 3   0.016 mg 10-15     11.54                                                                              4.95                                 BCNU     J + 3   0.1 mg   10-12     11.1 0.9                                  Methotrexate                                                                           J + 3   0.250 mg 15-17     15.9 44.62                                Endoxan  J + 3   4 mg     13-3 mice alive on 30th day/10                      ______________________________________                                    

                                      TABLE VI                                    __________________________________________________________________________                Quantity in                                                                   mg/mouse                                                                              Injection                                                                          Range of death                                                                        MTS                                                                              ILS %                                     __________________________________________________________________________    Control 10.sup.5 cells    9-10   9.06                                         Thiotepa      0.1 mg                                                                              J + 3                                                                               9-10   9.2                                                                              1.54                                      Mitomycine C  0.016 mg                                                                            J + 3                                                                               9-10   9.06                                                                             0                                         BCNU          0.1 mg                                                                              J + 3                                                                              8-9     8.8                                                                              0                                         Methotrexate  0.250 mg                                                                            J + 3                                                                              12-14   12.62                                                                            39.35                                                         J + 1                                                                               9-16   12.6                                                                             39.07                                     Compound of example 7                                                                       0.2 mg                                                                              J + 3                                                                              10-15   12.27                                                                            35.43                                     Endoxan         4 mg                                                                              J + 3                                                                              15-21   18.6                                                                             105.30                                    __________________________________________________________________________

                  TABLE VII                                                       ______________________________________                                        Compound In-                Range of                                          tested   jection Quantity   death  MTS  ILS %                                 ______________________________________                                        Control 10.sup.5            10-11                                             cells                                                                         Compound of                                                                            J + 3   0.2 mg/mouse                                                                             13-16  14.18                                                                              36.35                                 example 7                                                                     ON COVIN "       0.5 μg/mouse                                                                          10-13  10.8 3.85                                  ______________________________________                                    

                                      TABLE VIII                                  __________________________________________________________________________                           Quantity*      Number of                               Number of L 1210 cells                                                                         Compound                                                                            injected in    surviving                               injected on day J                                                                              used  mg/mouse                                                                              MTS                                                                              ILS %                                                                             mice                                    __________________________________________________________________________    10.sup.3    Controls                                                                           --    --      13                                                              Example 8                                                                           0.1 mg/mouse                                                                          16.4                                                                             50.5                                                                              3                                                        Example 8                                                                           0.05 mg/mouse                                                                         14.7                                                                             34.9                                                                              1                                                        Example 7                                                                           0.2 mg/mouse                                                                          16.3                                                                             25.4                                                                              7                                                        Example 7                                                                           0.1 mg/mouse                                                                          15 15.4                                                                              4                                       10.sup.4    Controls                                                                           --    --      10.9                                                                             --  --                                                       Example 7                                                                           0.1 mg/mouse                                                                          18 65.1                                                                              1                                                        Example 8                                                                           0.1 mg/mouse                                                                          13.7                                                                             25.7                                                                              3                                                        Example 8                                                                           0.05 mg/mouse                                                                         14.7                                                                             34.9                                                                              1                                       10.sup.5    Controls           9.05                                                            Example 8                                                                           0.1 mg/mouse                                                                          13.8                                                                             52.5                                                               0.05 mg/mouse                                                                         11.6                                                                             28.1                                        __________________________________________________________________________     *dose in mg/mouse × 50 = dose in mg/kg                             

                                      TABLE IX                                    __________________________________________________________________________                     Quantity of the compound                                     Number of L 1210 cells                                                                         of example 7 used in          Surviving                      injected on day J                                                                              mg/mouse     Injection MTS                                                                              ILS %                                                                             mice                           __________________________________________________________________________    10.sup.4    Controls                    11.9                                                   0.2 mg/mouse                                                                  4 × (0.05 mg/mouse)                                                                  single at 14.2                                                                             19.32                                                                             1                                                            J + 3, fraction-                                                                        14.4                                                                             21  0                                                            ated at                                                                       J + 3 + 4 + 5 + 6                               10.sup.5    Controls                    10.4                                                   0.2 mg/mouse single at 14.18                                                                            36.35                                               4 × (0.05 mg/mouse)                                                                  J + 3, fraction-                                                                        13.4                                                                             28.85                                                            ated at                                                                       J + 3 + 4 + 5 + 6                               __________________________________________________________________________

What is claimed is:
 1. A dipyrido [ 4,3-b] [3,4-f] indole of the formula##STR33## in which: R'₁ is hydrogen, hydroxy, lower alkyl, halogen or anamino group of the formula ##STR34## wherein n is an integer from 1 to3,R'₆ is hydrogen or lower alkyl, R'₄ and R'₅ each independently ishydrogen or lower alkyl, and R'₂ is hydrogen or lower alkyl, or apharmaceutically acceptable salt thereof.
 2. A compound according toclaim 1, wherein R'₂ is methyl and R'₁ is hydrogen or hydroxy.
 3. Acompound according to claim 1, wherein R'₂ is hydrogen and R'₁ ischloro.
 4. A compound according to claim 1, wherein R'₂ is methyl andR'₁ is halogen or an amino group of the formula ##STR35##
 5. A compoundaccording to claim 1, wherein R'₂ is hydrogen, and R'₁ is hydroxy,halogen or an amino group of the formula ##STR36##
 6. A compoundaccording to claim 5, wherein R'₆ is hydrogen or methyl and R'₄ and R'₅each independently is hydrogen methyl or ethyl.
 7. A compound accordingto claim 1, selected from the group consisting of5,11-dimethyl dipyrido[4,3-b] [;3,4-f] indole; 2,5,9,11-tetramethyl dipyrido [4,3-b] [3,4-f]indolinium diacetate; 5,11-dimethyl dipyrido [4,3-b] [3,4-f]indoleacetate; 5,11-dimethyl dipyrido [4,3-b] [3,4-f] indole dihydrochloride;1,2-dihydro-oxo-5-methyl dipyrido [4,3-b] [3,4-f] indole;1-chloro-5-methyl dipyrido [4,3-b] [3,4-f] indole;1[(γ-diethylaminopropyl) amino]5-methyl dipyrido [4,3-b 3,4-f] indole;1-[(γ-dimethylaminopropyl) amino]5-methyl dipyrido [4,3-b ] [3,4-f]indole; 1[(β-dimethylaminoethyl) amino]-5-methyl dipyrido [4,3-b] [3,4]indole; -1[(α-methyl-δ-diethylamino-butyl) amino]-5-methyl dipyrido[4,3-b] [3,4-f] indole; -1-[(γ-amino-propyl)amino]-5-methyl dipyrido[4,3-b] [3,4-f] indole; and 1,2-dihydro-1-oxo-5,11-dimethyl dipyrido[4,3-b] [3,4-f] indole.
 8. A process for preparing a compound accordingto claim 1, comprising the steps of:(1) reacting a 6-amino-isoquinolinewith 3-nitro-4-chloropyridine to form the corresponding6-[4'-(3'-nitropyridyl) amino] isoquinoline; (2) hydrogenating saidisoquinoline thus obtained into the corresponding amino compound; (3)reacting the corresponding amino compound with sodium nitrite to formthe corresponding triazolopyridine; (4) converting the triazolopyridinethus obtained into the corresponding dipyrido [4,3-b] [3,4-f] indole,and (5) optionally forming the pharmaceutically acceptable salt of thedipyrido indole thus obtained.
 9. A process according to claim 8,wherein the hydrogenation of step (2) is effected in the presence of ahydrogenation catalyst.
 10. A process according to claim 8, wherein step(4) is effected in the presence of an inert high melting material.
 11. Aprocess according to claim 8, wherein the 6-amino-isoquinoline is one ofthe tautomers ##STR37## and is obtained by converting the amino group ofa 2-methyl-3-amino-benzonitrile into an acetylamino group, convertingthe cyano group of the 2-methyl-3-acetylamino-benzonitrile into thealdehyde group, condensing the latter with malonic acid to form an acidof the formula ##STR38## forming the azide of the acid cyclizing to formthe corresponding isoquinolone, and eliminating the acetyl group fromthe amino group.
 12. A process according to claim 8, wherein the6-amino- isoquinoline is one of the tautomers ##STR39## and is obtainedby converting a 2-methyl-3-nitro-aniline into a(2-methyl-3-nitro-phenyl) chloropropionic acid, converting the lattercompound into a 2-methyl-3-nitro-cinnamic acid by elimination of HCl,converting the nitro group into the amino group and thenthe acetylaminogroup, cyclizing to form the corresponding isoquinolone, and eliminatingthe acetyl group from the amino group.
 13. A process according to claim8, wherein the 6-aminoisoquinoline is one of the tautomers ##STR40## andis obtained by converting the chloromethyl group of ##STR41## into analdehyde group, condensing this aldehyde group with malonic acid to formthe corresponding cinnamic acid, reducing the nitro group into an aminogroup, coverting the amino group into an acetylamino group, cyclizing toform the corresponding isoquinolone, and eliminating the acetyl groupfrom the amino group.
 14. A process according to claim 8, wherein R,¹ is##STR42## comprising the further steps of chlorinating the1,2-dihydro-1-oxo- 5-methyl-dipyrido [4,3-b] [3,4-f] indole, andreacting the chlorinated compound so obtained with the appropriateamine.
 15. A compound according to claim 1, wherein R'₂ is hydrogen. 16.A compound according to claim 1, wherein R'₂ is methyl.